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it STAOF CALIFORNIA -Environmental Prot* Agency • PETE WILSQ <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION _ <br /> 3443 Routier Road, Suite A - �� '+I t��L HEAI_Th <br /> Sacramento, CA 95827-3098 N..R I PRVIrF. <br /> PHONE: (916) 255-3000 e <br /> FAX: (916) 255-3015 ? 2'J PM 1: 10 <br /> 23 March 1994 <br /> Mr. David W. Bates <br /> Chief Production Engineer <br /> Marley Cooling Tower Company <br /> 5800 Foxridge Drive <br /> Mission, Kansas 66201 <br /> QUARTERLY GROUNDWATER MONITORING AND PERFORMANCE MONITORING, <br /> MARLEY COOLING TOWER COMPANY, SAN JOAQUIN COUNTY <br /> We have reviewed the Quarterly Full-Scale Soil Flushing, Groundwater Monitoring, Performance <br /> Monitoring and Well Construction Report submitted on 23 December 1993 by Dudek & Associate, <br /> Inc. (Dudek). We have also reviewed the Proposed Revisions to the Current Groundwater <br /> Monitoring Program submitted on 1 February 1994 by Dudek. This letter discusses our review of <br /> both documents pertaining to the Marley Cooling Tower Company (Marley) site. <br /> In general, we are pleased with the commitment of Marley toward the cleanup of the site. The <br /> submittal of these reports meets the requirements of Waste Discharge Requirements No.93-221, <br /> NPDES No. CA0081787 for ground water monitoring and evaluation/modification of the monitoring <br /> program as appropriate. The ground water extraction system is reported to have been operating on <br /> a continuous, non-cyclic, schedule since April 1993. However, based on review of chromium <br /> concentrations in the ground water in the deep zone, the extraction system has been unable to <br /> achieve plume capture. Increases can be seen in well D-2 suggesting a vertical downward migration <br /> of the contaminant plume. Increases are also apparent in agricultural wells identified as Main Street <br /> and Colombini 1 which represent continued horizontal migration. Pumping from the agricultural <br /> wells south of Main Street continue to dominate the flow regime, exacerbating contaminant <br /> migration horizontally as well as vertically and continue to prevent Marley from establishing full <br /> plume capture and cleanup. <br /> Chromium concentrations in the Colombini 1 irrigation well exceed drinking water standards and <br /> approach the agricultural limitation of 100 parts per billion (ppb). When considering the standard <br /> construction and screen lengths for agricultural wells, concentrations of 80 ppb chromium in the <br /> irrigation well could easily represent much higher actual concentrations within portions of the <br /> aquifer. This situation poses a threat to the beneficial uses of the ground water and Marley should <br /> notify the owners of the irrigation wells of the laboratory results, there significance and the effects <br /> of pumping on cleanup activities. <br />